With the growing acceptance of the Internet as a new dissemination medium, 
several new and interesting challenges arise in building a digital commerce 
infrastructure.  In this article we discuss some of the issues that arise
in building such an infrastructure.  In particular, we study how one can find
and pay for digital information, and how one can safeguard the information 
from invalid access and duplication.  We use examples from our Stanford 
Digital Library Project to illustrate some of these problems and their 
potential solutions.